In HD, this reduction could be due to the abnormal decrease in CBP protein levels, which has been reported to cause a downregulation of CREB dependent genes (Nucifora et al., 2001; Jiang et al., 2006; Giralt et al., 2012), such as BDNF, but also c-fos and egr1 (Shieh et al., 1998; Tao et al., 1998; Lonze and Ginty, 2002). Here, FOS is linked to Huntington disease.